A capo is a mechanical device that removably attaches to the neck of a stringed musical instrument, such as a guitar, to selectively change the key or pitch of the sound elicited from the instrument when the strings are played. A guitar capo, for instance, can be disposed along the neck of a guitar behind one of the frets of the guitar neck. The capo covers and presses against the strings of the instrument to change the key or pitch of the open operative strings located below the capo. Each fret of a guitar is a half step or a semi-tone higher or lower relative to other frets along the fret board. When a capo is placed behind a certain fret, the open operative strings below the fret, when played, emit chord sounds that are higher in key or pitch by the number of semi-tones of the fret. For instance, if the capo is placed behind the first fret, all the open strings will be raised one semi-tone. In this case, when a person plays a G chord, the chord sound is G#/Ab. When the capo is placed behind the second fret, the open strings are raised by a whole tone, such that, when a G chord is played, an A chord sound is produced. Similarly, when the capo is placed behind the third fret, the open strings are raised by three semi-tones and a G chord would sound like an A#/Bb chord. By using a capo, a person can play familiar chords relative to the capo, but would produce different chord sounds, and/or chord sounds that are more difficult to play without using a capo. In general, if the capo is placed behind an X fret, the chord sounds will be X semi-tones higher in key or pitch than the chord sounds elicited without the use of the capo.